/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.everrest.core.resource;

import org.everrest.core.ExtMultivaluedMap;
import org.everrest.core.impl.header.MediaTypeHelper;

import javax.ws.rs.core.MediaType;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author <a href="mailto:andrew00x@gmail.com">Andrey Parfonov</a>
 * @version $Id$
 */
public class ResourceMethodMap<T extends ResourceMethodDescriptor> extends HashMap<String, List<T>> implements
                                                                                                    ExtMultivaluedMap<String, T> {
    private static final long serialVersionUID = 8930689464134153848L;

    /**
     * Compare list of media types. Each list should be already sorted by
     * {@link MediaTypeHelper#MEDIA_TYPE_COMPARATOR}. So it is enough to compare
     * only last media types in the list. Last media types is the least precise.
     */
    private static final Comparator<ResourceMethodDescriptor> RESOURCE_METHOD_COMPARATOR =
            new Comparator<ResourceMethodDescriptor>() {
                @Override
                public int compare(ResourceMethodDescriptor o1, ResourceMethodDescriptor o2) {
                    int r = MediaTypeHelper.MEDIA_TYPE_COMPARATOR.compare(getLast(o1.consumes()), getLast(o2.consumes()));
                    if (r == 0) {
                        r = MediaTypeHelper.MEDIA_TYPE_COMPARATOR.compare(getLast(o1.produces()), getLast(o2.produces()));
                    }
                    if (r == 0) {
                        r = o1.consumes().size() - o2.consumes().size();
                    }
                    if (r == 0) {
                        r = o1.produces().size() - o2.produces().size();
                    }
                    return r;
                }

                private MediaType getLast(List<MediaType> l) {
                    return l.get(l.size() - 1);
                }
            };

    /** {@inheritDoc} */
    public List<T> getList(String httpMethod) {
        List<T> l = get(httpMethod);
        if (l == null) {
            l = new ArrayList<T>();
            put(httpMethod, l);
        }
        return l;
    }

    /** {@inheritDoc} */
    public void add(String httpMethod, T resourceMethod) {
        if (resourceMethod == null) {
            return;
        }
        List<T> l = getList(httpMethod);
        l.add(resourceMethod);
    }

    /** {@inheritDoc} */
    public T getFirst(String httpMethod) {
        List<T> l = getList(httpMethod);
        return l != null && l.size() > 0 ? l.get(0) : null;
    }

    /** {@inheritDoc} */
    public void putSingle(String httpMethod, T resourceMethod) {
        if (resourceMethod == null) {
            return;
        }
        List<T> l = getList(httpMethod);
        l.clear();
        l.add(resourceMethod);
    }

    /** Sort each collections in map. */
    public void sort() {
        for (List<T> l : values()) {
            Collections.sort(l, RESOURCE_METHOD_COMPARATOR);
        }
    }

    /**
     * Get HTTP method names to use it in 'Allow' header.
     *
     * @return collection of method names
     */
    public Collection<String> getAllow() {
        List<String> allowed = new ArrayList<String>();
        for (Map.Entry<String, List<T>> e : entrySet()) {
            if (!e.getValue().isEmpty()) {
                allowed.add(e.getKey());
            }
        }
        return allowed;
    }
}